1. Field of the Invention
The present invention relates to a power take off (PTO) control system for a work vehicle equipped with an implement, and particularly to hydraulic control of a PTO clutch.
2. Description of the Related Art
A tractor disclosed in Japanese Laid-open Patent Publication No. 2006-11843, which is one example of a work vehicle, comprises a hydraulic multi-plate PTO clutch that is able to transmit and interrupt power to an implement coupled to a machine body (see C3 of FIGS. 3 and 4 of the abovementioned document), a control valve for supplying hydraulic fluid to the PTO clutch (V4 of FIG. 7 of Patent Document 1), and a PTO clutch lever (43 of FIG. 7 of the abovementioned document). A driver operates the control valve in the tractor by operating the PTO clutch lever. When hydraulic fluid is supplied to the PTO clutch, the PTO clutch enters an engaged state, and when hydraulic fluid is discharged from the PTO clutch, the PTO clutch enters a disengaged state.
Coupling a variety of small- to large-size implements to the machine body allows the tractor to perform a variety of tasks.
The weight of a driven part and the starting torque of a small-sized implement are comparatively low, and therefore even when the PTO clutch is moved to the engaged state and power is transmitted to the small-sized implement, the shock when a drive is initially provided to the small-sized implement is a comparatively small amount. In contrast, the weight of the driven part and the starting torque of a large-sized implement (for example, a large grass mower) are comparatively large, and therefore when the PTO clutch is moved to the engaged state and power is transmitted to the large-sized implement, the shock when a drive is initially provided to the large-sized implement is a comparatively great amount.